The field of the present invention is plant molecular biology, especially as related to genetically modified plants with conditional male sterility. Specifically, the present invention relates to conditionally male and/or female sterile plants in which sterility is achieved by disrupting the availability of thiamine by high affinity binding proteins expressed in pollen and/or in the developing ovule, by inhibiting functional expression of one or more thiamine biosynthetic proteins or by destroying thiamine in those plant tissues.
Systems of plant sterility are essential tools in the hybrid seed industry, forestry, conservation biology, and phytoremediation. The hybrid seed industry plants millions of acres of in which one of the two elite parent plants in a genetic cross is male sterile as a result of physical or genetic emasculation. Male sterility is the basis for this 400 million dollar per year industry. Foresters are interested in plant sterility, because wood production is dramatically reduced when nitrogen and phosphorus are drained into pollen and megagametophyte production. In addition, genetically engineered trees, shrubs, and grasses are being developed that extract, detoxify, and/or sequester toxic pollutants and for phytomining of precious elements. Conditional male sterility adds value to and limits unauthorized propagation of valuable plants for any purpose. Plant sterility systems are needed if genetically modified organisms (GMOs) are to be released into the natural environment with no release of their germplasm. In this case, complete male-female sterility is desirable so that the organisms cannot reproduce seed by any means.
Numerous strategies have been used to generate male sterility for the hybrid seed industry ranging from manually emasculating plants, altering the levels of essential metabolites in pollen, and generating toxins in developing pollen with two component systems (Perez-Prat and van Lookeren Campagne, 2002). Another approach has been to make the essential vitamin cofactor biotin unavailable in reproductive tissues to render a plant sterile. Applying this harmless vitamin to the plants then restores fertility (Albertsen and Howard, 1999).
There is a need in the art for economical and safe compositions and methods for rendering plants male and/or female sterile, especially where the sterility can be controlled so as to allow the production of viable seeds under controlled conditions.